Speaking on NBC's 'The Tonight Show', Obama said Moscow sometimes slipped into a Cold War mentality, despite being co-operative with the United States on some issues, including counter-terrorism efforts in the aftermath of the Boston Marathon bombing.

"There have been times where they slip back into Cold War thinking and a Cold War mentality," he said.

"What I say to President Putin is, that's the past and...We've got to think about the future. And there's no reason why we shouldn't be able to cooperate more effectively than we do."

Asked whether the controversial surveillance programmes helped lead to the intelligence that sparked the warnings, Obama said the programmes were critical to counter-terrorism work. But he said more needed to be done to assure Americans they were not being spied on themselves.

We don't have a domestic spying programme. What we do have are some mechanisms where we can track a phone number or an email address that we know is connected to some sort of terrorist threat.

– Barack Obama

The odds of dying in a terrorist attack were less than dying in a car accident, Obama said, and Americans should be careful but did not need to cancel planned holidays to places such as Europe, as a result of the recent travel warnings.

In lighter notes, Obama said he had invited his former secretary of state, Hillary Clinton, to her recent lunch at the White House and described her as having a post-administration "glow"."We have become genuinely close, and I could not have more respect for her," Obama said.

Asked by Leno whether the former first lady and potential 2016 presidential candidate had "measured the drapes" while she was there, Obama said no.

"Keep in mind she's been there before," he joked. "She doesn't have to measure them."

Leno also poked fun at Obama for having told a group of young people that broccoli was his favorite food.